City Line depresses working academic (6)
I believe the answer is:
london
'city' is the definition.
(I know that London is a city)
'line depresses working academic' is the wordplay.
I cannot really see how this works, but
'line' could be 'l' (used when specifying particular lines from a poem) and 'l' is present in the answer.
'working' could be 'on' (e.g. a machine is working or on) and 'on' is found in the answer.
'academic' could be 'don' (type of academic - especially at Oxbridge) and 'don' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for london that I've seen before include "England's capital city" , "UK's capital" , "- Clay; - pride; - plane" , "UK Capital city" , "source of this paper" .)